[
    {
        "id": "authors:461e1-tsj53",
        "collection": "authors",
        "collection_id": "461e1-tsj53",
        "cite_using_url": "https://authors.library.caltech.edu/records/461e1-tsj53",
        "type": "book",
        "title": "Tracking Multiple-Mode Frequency Changes in a 10-Story Cold-Formed Steel Building to Assess Damage",
        "book_title": "Proceedings of the 13th National Conference on Earthquake Engineering",
        "author": [
            {
                "family_name": "Guo",
                "given_name": "Huiyun",
                "orcid": "0000-0002-8516-4244",
                "clpid": "Guo-Huiyun"
            },
            {
                "family_name": "Zhang",
                "given_name": "Shun (Shane)",
                "clpid": "Zhang-Shun-Shane"
            },
            {
                "family_name": "Kohler",
                "given_name": "Monica D.",
                "orcid": "0000-0002-4703-190X",
                "clpid": "Kohler-M-D"
            },
            {
                "family_name": "Guy",
                "given_name": "Richard"
            },
            {
                "family_name": "Sorosh",
                "given_name": "Shokrullah"
            },
            {
                "family_name": "Zhang",
                "given_name": "Jiachen"
            },
            {
                "family_name": "Hutchinson",
                "given_name": "Tara C."
            }
        ],
        "abstract": "<p>We report frequency\u2010domain observations from a full-scale, 10-story, cold-formed steel building tested on the 6-degrees-of-freedom Large High-Performance Outdoor Shake Table at UC San Diego where 76 triaxial Community Seismic Network&nbsp;accelerometers recorded continuous waveforms prior to, during, and after increasing-intensity earthquake tests. Spectrograms&nbsp;of the continuous ambient data reveal persistent, elevation-dependent bands of high energy at both fundamental and higher&nbsp;building modes. During a representative earthquake input (<em>MID</em>16, 1989 <em>Mw</em> 6.9 Loma Prieta motion scaled at Design&nbsp;Earthquake level), the data from a sensor at Level 7, for example, shows that the fundamental mode frequencies decrease at the&nbsp;onset by ~0.60 Hz (X direction, EW) and ~0.55 Hz (Y direction, NS), and recover within ~50 s to final residual reductions of&nbsp;about 0.1 Hz. The third mode shows a larger permanent decrease (~0.2 Hz). These results are consistent with transient softening and frictional slip during the test followed by small but measurable residual stiffness changes afterward. Stiffness loss is confirmed by observed physical damage, most notably rotation and pull-through of fasteners&nbsp; attaching gypsum sheathing to CFS-framing.</p>",
        "doi": "10.7907/461e1-tsj53",
        "publisher": "Earthquake Engineering Research Institute",
        "publication_date": "2026"
    }
]